What Makes Us Unique

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Marilyn

Marilyn: You once wrote about why each human is biologically unique. We’re trying to recall the particular term you used in that explanation–regarding the moment of the sperm meeting the egg. Could you repeat the explanation?

Marilyn responds:

Actually, the term refers to a process that takes place before the sperm meets the egg. Long before conception, back when each egg and each sperm is first formed, a series of actions called meiosis (my-OH-sis) occurs. During meiosis, every future parent’s own deck of chromosomes is shuffled. The result is that each egg and each sperm gets a brand-new combination of genes.

So a woman’s eggs do not have her own individual recipe from the family gene pool. Neither do a man’s sperm. And as the number of possible new combinations is vast, every egg and sperm can be considered unique.

Then there’s the randomness of which sperm fertilizes which egg. It’s no wonder that brothers and sisters don’t look more alike. Children are not “half Mom + half Dad”. Instead, half of one’s genes are a shuffled combination from Mom’s side of the family; the other half are from Dad’s side.